1. Field of the Invention
This invention relates to a workpiece steadyrest and more particularly to a three-contact point workpiece steadyrest wherein all the contact shoes are simultaneously movable.
2. Description of the Prior Art
Presently most cam grinding machines utilize workpiece steadyrests having contact shoes which are set at a fixed position. In these prior art cam shaft steadyrests the fixed contact shoes are set to support a main bearing having a maximum within tolerance outer diameter. Cam shafts having main bearings of a smaller diameter are loose in the steadyrest, while cam shafts having over-tolerance main bearings are marked due to excessive gripping pressure and/or have their cams ground improperly.
U.S. Pat. No. 3,736,114 shows a steadyrest having three simultaneously movable contact shoes for engaging a workpiece. The main body of the steadyrest has a bore which receives a rotatable sleeve. A shaft is slidably contained in the sleeve and moved axially as the sleeve rotates. The center steadyrest shoe is provided at the free end of the shaft. The upper and lower contact shoes are pivotally mounted on the main body and are responsive to rotation of the sleeve for movement toward and away from the workpiece.